In many cases, wastes or refuse, such as municipal refuse and industrial wastes, contain chlorine in the form of polyvinyl chloride resin wastes mixed in them. These chlorine-containing wastes emit exhaust gases containing hydrogen chloride when burned. For example, municipal refuse, when burned, emits an exhaust gas which usually contains 500 to 1000 ppm hydrogen chloride. Polyvinyl chloride resin wastes, when burned alone, also emit an exhaust gas which usually contains 2 to 3% hydrogen chloride. When such exhaust gases are discharged into the atmosphere without treatment a pollution problem arises. Therefore, it is necessary to remove hydrogen chloride from the exhaust gases, before they are discharged into the atmosphere.
Heretofore, in order to remove hydrogen chloride from exhaust gases, the so-called wet type gas purifying method has been adopted wherein the exhaust gases are brought into contact with water to absorb hydrogen chloride. In the wet-type method, the waste water containing absorbed hydrogen chloride is neutralized by adding thereto an inorganic compound such as calcium carbonate, and after neutralization, the waste water is discharged, for example, into sewage. However, where hydrogen chloride is removed from the exhaust gases by the wet scrubbing method, the waste water discharged into sewage contains a considerable amount of dissolved inorganic compounds. There is a fear of these inorganic compounds cause water pollution, though they are not directly harmful to aquatic life. The exhaust gases sometimes contain various heavy metals derived from the chlorine-containing wastes. When exhaust gases containing such heavy metals are treated according to the wet scrubbing method, therefore, these heavy metals result in water pollution. In view of these facts, it is desirable to remove hydrogen chloride from exhaust gases without discharging waste water.